Under normal conditions, human intra-abdominal pressure is averagely zero or approximate to zero, but many clinical diseases can cause intra-abdominal pressure to increase. The causes include acute and chronic factors. The former includes large dilatation of hollow organs, edema and exudation of abdominal internal organs, intraperitoneal hemorrhage, and the use of intra-abdominal stuffing. The latter includes the growth of tumors. Continuous increase of intra-abdominal pressure may cause intra-abdominal hypertension. The incidence rate of intra-abdominal hypertension in patients with urination disorder, especially in high-risk surgical patients with urination disorder is generally 5%-40%. In severe cases, it may lead to abdominal compartment syndrome.
The abdominal compartment syndrome may cause a change in the hemodynamic force throughout the body; meanwhile, it may cause incompetence of the circulatory system, respiratory system, urinary system, and digestive system due to breathing restriction. In severe cases, it may cause the patients to suffer from oliguria, anuria, dyspnea, even multiple organ failure, resulting in deadly danger.
For postoperative care for some operation patients, measuring and monitoring the change in abdominal pressure is also an important part to prevent postoperative complications and ensure the patient's uneventful recovery.
In the existing technology, there are several methods for monitoring abdominal pressure as follows:
Direct manometric method: a water manometer or pressure sensor, or a laparoscope pneumoperitoneum machine, or an implanted inflation bag can be used to directly measure the abdominal pressure by placing a catheter or a thick needle in the abdominal cavity;
Indirect manometric method: the abdominal pressure is indirectly measured by measuring the pressure of rectum, stomach, postcava and bladder. The indirect manometric method of bladder pressure is simple and practical, which is known as the gold standard among the indirect manometric methods. Specifically, the method includes firstly emptying the bladder, infusing normal saline, connecting with a pressure sensor, then taking the symphysis position as zero point and measuring at the end of expiration. Other methods: in recent years, there are some new pressure measuring methods, for example, the blood pressure measuring function of the electrocardiogram monitoring (ECG) monitor is used for this purpose.
However, the existing monitoring methods for the abdominal pressure have the following defects:
Although the direct manometric method is accurate for the abdominal pressure measurement, it cannot be effectively promoted due to potential traumatic and infectious risks;
For the indirect manometric method, normal saline must be injected into the bladder before each pressure measurement; only interval pressure measurement can be carried out; air intake or air leakage within the bladder occurs easily; meanwhile, repeated operation may bring great pain and infection risk to the patients;
The pressure measurement method with the ECG monitor often uses blood pressure measuring resource during electrocardiogram monitoring, and is inconvenient to spread in clinical practice.
Therefore, in the clinical care and treatment presently, the above means can only be used when the abdominal pressure data is required indeed according to physical conditions of monitored patients. In other words, current clinical methods cannot monitor the abdominal pressure in real time, whereas the abdominal compartment syndrome cannot be accurately judged just according to the clinical manifestation, and it probably leads to delay and miss of good treatment opportunity because no abdominal pressure is obtained.